Automotive alignment lift

ABSTRACT

A parallelogram lift in which the deck rails are raised by lifting legs affixed to sliding members that slide within channels in the deck rails. Link arms pivotally connect to the deck rail to each leg, so that the deck rail lifts vertically. A single hydraulic actuator is used to actuate the legs supporting each deck rail, which ensures that the deck rail remains level during the lifting and lowering processes. In the preferred embodiment the hydraulic system is serially coupled between the hydraulic cylinders associated with each deck rail, which ensures that the displacement of hydraulic pistons raising both deck rails is synchronous so that the two deck rails are lifted at the same rate and remain horizontally aligned throughout lifting and lowering, and an incremental braking system is provided which automatically locks the deck rails into any desired elevated position, reducing the load on the hydraulic system and providing a failsafe against free-falling of the deck rails in the event of hydraulic failure.

FIELD OF INVENTION

This invention relates to lift systems. In particular, this inventionrelates to an automotive lift having improved lifting and stability.

SUMMARY OF THE INVENTION

Automotive lift systems are used to enable the inspection and repair ofan automotive vehicle from beneath the vehicle. For many decadesautomotive lift systems were in-ground post systems in which ahydraulically actuated central post supported a platform or deck, toraise the vehicle and maintain it in an elevated position for repair andservicing. Often service personnel worked in a bay recessed into thefloor beneath the lift.

More recently, above-ground systems have been developed in which theentire lift system is disposed above floor level. Such systems provideenvironmental advantages, because the hydraulic fluids which actuate thelift are often toxic so their use and storage underground should beavoided. Above-ground systems also simplify the design of the floor inthe area of the service bay.

One type of above-ground automotive lift is known as a parallelogramlift in which the supporting platform, typically a pair of deck railsaligned with the vehicle's wheels, is raised on sets of legs which pivotin relation to the deck rails. By increasing the angular relationbetween the deck rails and the legs of the lift, the deck rails can bemaintained relatively level while being raised to the desired height.This eliminates the central post, allowing service personnelunobstructed access to the underside of the vehicle. An example of suchan automotive lift is described in U.S. Pat. No. 5,096,159 issued Mar.17, 1992 to Fletcher, which is incorporated herein by reference.

However, such parallelogram lifts give rise to a number of problems.Because of the pivot connection between the legs of the lift and thedeck rails, as the lift is raised the deck rails move in an arc, i.e.horizontally as well as vertically. This requires a large clear space atone end of the lift, to accommodate the horizontally shifting positionof the deck rails during lifting and lowering. This can also pose ahazard to personnel or equipment positioned in the area into which thelift moves.

Moreover, because the level of the deck rails is determined by the pitchof at least four independently actuated legs, it is extremely difficultto maintain both deck rails properly levelled, and at the same levelrelative to each other, throughout the lifting and lowering processes.For some servicing procedures, for example wheel alignments, it isessential that the deck rails be maintained in almost perfect horizontalalignment. This requires very close synchronization between the separatehydraulic cylinders that actuate the legs of the lift.

In the event that one of the hydraulic actuators fails, the legassociated with the failed actuator can collapse, with potentiallydisastrous results. Moreover, unlike a post lift system, in aparallelogram lift system the weight borne by the hydraulic systemincreases as the lift is lowered and the legs assume a greaterangulation relative to the deck rails and floor. This can presentproblems in the stability of the elevated deck rails, particularly atlower positions.

The present invention addresses these and other disadvantages ofautomotive parallelogram lift systems. In the preferred embodiment ofthe lift of the present invention, the legs are not pivotally connecteddirectly to the deck rails. Each leg has an associated link armconnected to the deck rail and to the leg, and the upper end of each legis slidably received by the deck rails. By positioning the connectionbetween each link arm to its associated leg at about the midpoint of theleg, the lift rises vertically. This significantly reduces the spacerequirements of the lift, and avoids the potential hazard to personnelor objects positioned at either end of the lift.

According to the preferred embodiment of the invention a singlehydraulic actuator is used to actuate the legs supporting one deck rail,which ensures that the deck rail remains level at all times duringlifting and lowering. Further, in the preferred embodiment the hydraulicsystem is serially coupled between the hydraulic cylinders associatedwith each deck rail, i.e. the discharge of fluid from one hydrauliccylinder drives the other hydraulic cylinder, which ensures asynchronous displacement of both hydraulic pistons is so that the twodeck rails are raised at the same rate and remain horizontally alignedthroughout lifting and lowering.

Also, in the preferred embodiment an incremental braking system isprovided which automatically locks the deck rails into any desiredelevated position. This reduces reliance upon the hydraulic system andprovides a failsafe against free-falling of the lift in the event ofhydraulic failure.

The present invention thus provides an automotive lift comprising a pairof lifting sections, each lifting section comprising a deck rail forsupporting a vehicle, supported by at least two legs, each leg having anassociated sliding assembly to which an upper portion of the leg ispivotally affixed, slidably mounted to the deck rail and having a pathof travel along a portion of the length of the deck rail, and anassociated link arm, having an upper end pivotally secured to the deckrail at a fixed position spaced from the path of travel of the slidingassembly and a lower end pivotally secured to an intermediate portion ofthe leg, and an actuator for applying a force to each sliding assembly,whereby the actuator forces each sliding assembly to move toward itsassociated link arm to alter an angulation between the leg relative tothe deck rail.

The present invention further provides an automotive lift comprising apair of lifting sections, each lifting section comprising a deck railfor supporting a vehicle, supported by at least two legs, each leghaving an associated sliding assembly to which an upper portion of theleg is pivotally affixed, slidably mounted to the deck rail and having apath of travel along a portion of the length of the deck rail, and anassociated link arm, having an upper end pivotally secured to the deckrail at a fixed position spaced from the path of travel of the slidingassembly and a lower end pivotally secured to an intermediate portion ofthe leg, and a hydraulic cylinder secured at a fixed position on thedeck rail to apply a force longitudinally along the deck rail, having apiston with a piston shaft extending from forward and rear ends of thecylinder, a forward end of the piston shaft being coupled to a forwardsliding assembly and a rear end of the piston shaft being coupled to arear sliding assembly, to move the forward and rear sliding assembliesin synchronous relation, the actuator forces each sliding assembly tomove toward its associated link arm to alter an angulation between theleg relative to the deck rail and thus raise the deck rail.

The present invention further provides an automotive lift comprising apair of lifting sections, each lifting section comprising a deck railfor supporting a vehicle, supported by at least two legs, each leghaving an associated sliding assembly to which an upper portion of theleg is pivotally affixed, slidably mounted to the deck rail and having apath of travel along a portion of the length of the deck rail, the pathof travel having at least one row of slots extending along a portion ofthe length of the deck rail, and an associated link arm, having an upperend pivotally secured to the deck rail at a fixed position spaced fromthe path of travel of the sliding assembly and a lower end pivotallysecured to an intermediate portion of the leg, and an actuator forapplying a force to each sliding assembly, whereby the actuator forceseach sliding assembly to move toward its associated link arm to alter anangulation between the leg relative to the deck rail, wherein eachsliding assembly is provided with a pair of brake arms retractable froman extended position in which the brake arms extend into the slots to aretracted position in which the brake arms are retracted from the slots,the brake arms being biased toward the slots and being retractable aforce applied to the brake arms.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate by way of example only a preferredembodiment of the invention,

FIG. 1 is a perspective view of a preferred embodiment of an automotivelift embodying the invention,

FIG. 2 is a side elevation of the automotive lift of FIG. 1 showing thelift in a lowered position,

FIG. 3 is a side elevation of the automotive lift of FIG. 1 showing thelift in a raised position,

FIG. 4 is a cutaway elevation of showing the movement of the deck railduring lifting,

FIG. 5 is a cutaway perspective view of one deck rail,

FIG. 6 is a top plan view of a preferred embodiment of the brakingmechanism showing the brake engaged to the deck rail,

FIG. 7 is a top plan view of the braking mechanism of FIG. 6 showing thebrake in a release position,

FIG. 8 is an exploded view of the braking mechanism of FIG. 6, and

FIG. 9 is a side elevation of the hydraulic system for a furtherembodiment of the automotive lift of the invention having three legs ineach lift section.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 3 illustrate a preferred embodiment of the automotive lift 10of the invention. The lift 10 conventionally comprises a pair of liftsections 10a, 10b respectively provided with deck rails 20a and 20b,which when installed are substantially parallel and are spaced apart adistance approximating the distance between the wheels of an automotivevehicle 2.

The width of each deck rail 20 is sufficient to accommodate thethickness of the vehicle's tires and varying wheelbase lengths ofdifferent vehicles 2, with sufficient clearance between the deck rails20 to permit servicing and repairs to the underside of the vehicle 2.The deck rails 20 are preferably respectively provided with a fixedfront barrier plate 22 to ensure that a vehicle is properly restrainedon the deck rails 20, and a pivoting rear plate 24 which when the lift10 is in the lowered position shown in FIG. 2 forms a ramp between thefloor 26 of the deck rail 20 and the floor 4 of the service bay, whichallows the vehicle 2 to be driven on and off of the lift 10.

The structure of the automotive lift of the invention will hereinafterbe described in relation to one deck rail 20 (identified as 20a inFIG. 1) and the lifting and braking mechanisms associated therewith, itbeing appreciated that the structure of the other deck rail 20 (20b inFIG. 1) is substantially identical in the preferred embodiment. All ofthe lift components described below are preferably formed from hardenedsteel or another suitably rigid and structurally sturdy material.

The deck rail 20 is supported by lifting legs 30. According to apreferred embodiment of the invention, two lifting legs 30 are pivotallysecured at their lower ends 32 to floor anchor plates 40 which arebolted to the floor 4 of the service bay in conventional fashion, andare pivotally secured at their upper ends 34 to sliding assemblies 50engaged into channels 28 formed within the substructure of the deck rail20, as shown in FIG. 5. Each lifting leg 30 comprises a pair of rigidsupporting members 31 welded together by cross-plates 33, for greaterstrength.

In the preferred embodiment the sliding assemblies 50, illustrated inFIGS. 6 to, comprise a sliding body 52 welded or otherwise affixed towings 54 disposed vertically within the channels 28. The wings 54 areprovided with low-friction slide blocks 56 which allow the wings 54 toslide relatively freely within the channels 28, so that each slidingassembly 50 can move along a path of travel defined by a portion of thelength of the deck rail 20.

Each leg 30 is tied to the deck rail 20 by a link arm 42 having an upperend pivotally secured to the deck rail 20 at a fixed position spacedfrom the path of travel of the sliding assembly 50, as at link arm mount43 welded to the deck rail 20 as shown in FIG. 5, and a lower endpivotally secured to an intermediate position on the leg 30. The angularrelation of the link arm 42 relative to the upper portion of the leg 30decreases in a toggle fashion as the sliding assembly 50 slidesrearwardly along the deck rail 20. Thus, as the sliding assembly 50attached to the top end 34 of each leg 30 slides rearwardly along theunderside of the deck rail 20, the angular relation of the leg 30relative to the deck rail 20 (and thus relative to the floor 4)increases, which raises the deck rail from the lowered position shown inFIG. 2 to a raised position such as that shown in FIG. 3.

This configuration causes the deck rails 20 to rise vertically as thelift 10 is raised, as shown in FIG. 4. Optimal leverage is obtained whenthe link arm 42 is secured to its associated leg 30 at approximately themidpoint of the leg 30 as shown in the preferred embodiment illustrated.The length of the link arm 42 is preferably approximately one half ofthe length of the leg 30 in the preferred embodiment, so that in thelowered position shown in FIG. 2 the link arm 42 does not extendsubstantially beyond the bottom end 32 of the leg 30.

Thus, according to the invention the deck rail 20 is raised by applyinga force to the sliding assemblies 50 to force them rearwardly along thechannels 28, decreasing the angulation between the link arms 42 and theupper portions of the legs 30 and at the same time increasing theangular relation of the legs 30 relative to the deck rail 20 (and floor4). In the preferred embodiment this is accomplished by providing ahydraulic actuator comprising a hydraulic cylinder 70 mounted at a fixedposition, preferably concealed underneath the deck rail 20, between therespective paths of travel of the sliding assemblies 50. The hydrauliccylinder 70 is welded to any fixed component of the deck rail 20, forexample the link arm mount 43 as illustrated in FIG. 5.

The hydraulic cylinder 70 drives a piston shaft 72 which projects out ofboth ends of the cylinder 70. The front end 74 of the piston shaft 72 isaffixed to the front sliding assembly 50, and the rear end 76 of thepiston shaft 72 is affixed to the rear sliding assembly 50. The slidingassemblies 50 thus slide synchronously along the channels 28, thedistance between the front and rear sliding assemblies 50 being fixed bythe length of the piston shaft 72.

The deck rail 20 is thus raised and lowered by changing the axialposition of the piston shaft 72 relative to the hydraulic cylinder 70.To raise the deck rail 20 the piston shaft 72 is driven rearwardly,forcing the rear sliding assembly 50 (shown at the left in FIGS. 2 and3) rearwardly; at the same time the front sliding assembly 50 (shown atthe right in FIGS. 2 and 3) is drawn rearwardly in tandem with the rearsliding assembly 50. This synchronizes the change in the angulation ofboth legs 30 relative to the deck rail 20 and ensures that the deck rail20 remains level at all times during lifting and lowering.

The hydraulic system further comprises a conventional hydraulic pump 81controlled from (and preferably contained within) a remote operator'sstation 80, shown schematically in FIG. 1. The pump 81 is coupled to theinlet of one hydraulic cylinder (70a in FIG. 1) through hose 82. Theoutlet of the cylinder 70a is coupled to the inlet of the otherhydraulic cylinder (70a in FIG. 1) through hose 84. The outlet ofcylinder 70b discharges the hydraulic fluid back to the pump 81 throughhose 86. The hydraulic cylinders 70a, 70b are thus effectively connectedto the hydraulic pump 81 in series. This ensures that the two liftsections 10a, 10b are retained at the same level relative to each otherat all times, because when the hydraulic cylinders 70 are operating(assuming that there are no leaks and all air has been bled from in thesystem) the exact same volume of hydraulic fluid is pumped through eachhydraulic cylinder 70a, 70b to displace the piston shafts 72a, 72b bythe same amount.

The hoses 82, 84, 86 should be securely fastened underneath the deckrails 20 and along the legs 30 and floor 4 (as by guard plate 87) so asnot to obstruct the workspace beneath the lift 10.

In the preferred embodiment the piston 72 is secured through a pistonblock 78 and retained by a nut 73. The piston block 78 is affixed to thesliding assembly 50 by pins 77 which extend through the upper end 34 ofthe lifting leg 30 and are pivotally received in mounting blocks 79welded to the wings 54 of the sliding assembly 50. Thus, the pins 77serve the dual purpose of securing the piston 72 to the sliding assembly50 and providing a structure about which the leg 30 can pivot as itsangular relation to the deck rail 20 changes during lifting andlowering.

In the preferred embodiment the invention provides an incrementalbraking mechanism which locks the sliding assemblies 50 into positionwithin the channels 28 at the desired elevation of the deck rail 20. Thebraking mechanism allows the deck rail 20 to be set to virtually anydesired elevated position, and provides a means for preventingfree-falling of the deck rail 20 in the event of hydraulic systemfailure.

A preferred embodiment the braking mechanism is illustrated in FIGS. 6to 8. The braking mechanism comprises a brake arms 100 pivotally securedto the sliding body 52. Each brake arm 100 preferably comprises alatching portion 102 secured to an actuating portion 104 by an obroundpin or bolt 106 that rotationally locks the latching portion 102 to theactuating portion 104 and engages into mount 108 to serve as a pivotpoint for the brake arm 100.

The brake arms 100 are biased to the extended or braking position shownin FIG. 6, and can be pivoted about the pins 106 to the retractedposition shown in FIG. 7 by drawing shackle 60 rearwardly. The shackle60 is provided with slots 62 for receiving bolts or other suitablefasteners 64 affixed to the actuating portions 104 of the brake arms100, the slots 62 being obliquely oriented to accommodate the change inlateral spacing between the actuating portions 104 as the brake arms 100pivot between the retracted and extended positions.

The brake arms 100 cooperate with opposed rows of slots 29 disposedalong the side wall of each channel 28, each slot 29 being large enoughto receive the latching portion 102 of a brake arm 100. The slots 29 canbe cut through the floor of the channel 28, but are preferably formedthrough a steel bar 27 which is then welded to the floor of the channel28, and preferably the row of slots 29 extends along substantially theentire path of travel of the sliding assembly 50 (as best seen in FIG.4). The slots 29 can be spaced apart at any selected interval, it beingdesirable to space the slots 29 as closely as possible so long assufficient material remains between the slots 29 to safely retain thesliding assembly 50 in position under the weight of the vehicle 2. Thus,depending upon the type and thickness of material in which the slots 29are formed, the sliding assemblies 50 can be locked into successivepositions along the channel 28 in increments which may be as small as afew inches.

The wings 54 of the sliding assembly 50 are provided with notches 55into which the latching portions 102 of the brake arms 100 recede andagainst which the brake arms 100 bear when in the extended position, toprevent the brake arms 100 from collapsing rearwardly (i.e. beyond the180° extended position) under the weight of an automobile 2. The brakearms 100 are retracted into the release position shown in FIG. 7 by anysuitable retracting means, in the embodiment illustrated a conventionalpneumatic cylinder 110 which is mounted beneath the piston block 78 andhas a piston 112 secured to the shackle 60. The piston 112 isspring-loaded, as by spring 111 (see FIG. 6) to revert to the fullyextended position in the absence of pneumatic pressure, which in turnbiases the shackle 60 and the brake arms 100 to the extended (braking)position. The pneumatic cylinder 110 is actuated by a compressor (notshown) controlled at the operator's station 80. The retracting meanscould alternatively be an electrical solenoid, motor or any other meanscapable of applying a pulling force to the shackle 60, and the inventionis not intended to be so limited.

It will be appreciated that both the front and rear sliding assemblies50 are oriented in the same direction, with the shackle 60 at the rearof each sliding assembly 50, so that the braking mechanisms both operatein the same direction. The front end 74 of the piston 72 approaches thefront sliding assembly 50 from the rear, however the rear end 76 of thepiston 72 approaches the rear sliding assembly 50 from the front andmust therefore extend over the sliding assembly 50 in order to couple tothe piston block 78, as shown in FIG. 5. Thus, the sliding body 52 isprovided with an arcuate upper edge, as shown in FIG. 8, or is otherwiseconfigured to allow the rear end 76 of the piston 72 to extend over thesliding body 52 and to the shackle 60 of the rear sliding assembly 50.

It can be seen that the rows of slots 29 are generally centred withinthe channels 28, however the actuating portions 104 of the brake arms100 are drawn from beneath the sliding body 52. Thus, a spacer block 109spaces the latching portions 102 of the brake arms 100 from theactuating portions 104, which raises the latching portions to the levelof the slots 29. The spacer block 109 is preferably a single piecethrough which both obround pins 106 pass, and is preferably welded tothe sliding body 52 leaving just enough space between the spacer block109 and the mounting blocks 108 to allow the latching portions 102 topivot therebetween. This helps to maintain the latching portions 102 ofthe brake arms 100 in proper alignment with the slots 29.

To install the lift 10 of the invention, one lift assembly 10a issecured to the service bay floor 4 in a vertical orientation by boltingor otherwise securing the anchor plates 40 to the floor 4. The otherlift assembly 10b is located so as to be parallel and alignedfront-to-rear with the lift assembly 10a, and spaced therefrom accordingto the wheelbase length of the vehicles 2 to be serviced on the lift 10,and is secured to the service bay floor 4 in like fashion. The hydraulicsystem is installed, care being taken to ensure that the hoses 82, 84,86 are secured away from the workspace beneath the lift 10 and will notbe crimped or pinched by any of the moving parts of the lift 10. Thedeck rails 20 are set to the lowered position and any entrained air isbled from the hydraulic system.

In operation, an automotive vehicle 2 is driven up to the rear plates 24and onto the deck rails 20, to the position shown in FIG. 2. The deck anoperator at the remote station 80 by actuating the hydraulic pump 81. Ashydraulic fluid is pumped into the cylinder 70a through hose 82 it isdischarged from the cylinder 70a through hose 84 to the cylinder 70b.The hydraulic pressure forces the hydraulic pistons 72 rearwardly, whichdisplaces the piston shafts 72 in unison toward the rear of the lift 10.The rearward motion of the piston shafts 72 overcomes the biasing forceof the spring-loaded pneumatic cylinders 110, retracting the latchingportions 102 of the brake arms 100 from the slots 29, and forces thesliding assemblies 50 to slide rearwardly which in turn causes the deckrails 20 to rise as the angular relation between the legs 30 and thedeck rails 20 increases. As the deck rails 20 rise off of the floor 4the rear plates 24 pivot to a vertical or oblique position and form abarrier against the vehicle 2 rolling off of the rear of the lift 10, asshown in FIG. 3.

It will be noted that the rear edges of the latching portions 102 arerounded, which allows the brake arms 100 to disengage from the slots 29under the force of the hydraulic cylinders 70. However, the biasingforce of the spring-loaded pneumatic cylinders 110 remains present sowhen the desired elevation has been reached, the operator merelyreleases the hydraulic pressure and the brake arms 100 are urged back tothe extended position. The deck rails 20 fall slightly as the weight ofthe vehicle 2 forces the sliding assemblies 50 forwardly, causing thebrake arms 100 to engage securely into the nearest opposed slots 29. Therounded rear edges of the brake arms 100 also facilitate the brake arms100 latching into the nearest slot 29 upon release of the hydraulicpressure. However, the latching portions 102 of the brake arms 100 havesquared front edges, to ensure that the leading edges of the brake arms100 securely engage into the slots 29.

Once the brake arms 100 have latched into the slots 29, the slidingassemblies 50 are restrained against further forward movement. Since asbetween the tow deck rails 20a, 20b the rows of slots 29 are in precisealignment, any slight deviation in the level of one deck rail 20arelative to the other deck rail 20b is corrected as the slidingassemblies 50 settle forwardly and the brake arms 100 engage into theslots 29.

The brake arms 100 thus lock the deck rails 20 in the elevated positionwithout the need to maintain the hydraulic pressure, by restraining thesliding assemblies 50 from sliding forwardly. It will thus be apparentthat in the event of hydraulic failure during the lifting process, assoon as the hydraulic pressure is released the brake arms 100 will pivotto the extended position under the force of the spring-loaded pneumaticcylinders 110 and engage the slots 29 as shown in FIG. 6, to preventfree-falling of the lift 10. For this reason it is advantageous toprovide slots 29 along the entire path of travel of each slidingassembly 50, even if it is unlikely that the lift 10 will be raised to alow elevation, to provide a failsafe against free-falling of the lift 10at any point during the lifting process.

To lower the deck rails 20 the hydraulic pump 81 is activated,displacing the pistons 72 rearwardly and thereby forcing the shackles 60to retract the brake arms 52. The deck rails 20 are raised slightly,enough to release the pressure from the brake arms 100. The pneumaticcylinders 110 are then engaged to retract the brake arms 100 from theslots 29. The hydraulic pressure is reduced, to allow for a controlledlowering of the deck rails 20 while maintaining the pneumatic pressureto retain the brake arms 100 in the retracted position shown in FIG. 7.The weight of the vehicle 2 causes the front and rear sliding assemblies50 to slide forwardly along the deck rails 20 in synchronous relation asthe piston shafts 72 are displaced forwardly through the cylinders 70,until the lift 10 has reached the lowered position shown in FIG. 2 atwhich point the pneumatic pressure can be released.

Optionally a failsafe switch (not shown) activated when the lift 10 isbeing lowered may be coupled to the operator's station 80, toautomatically stop the lowering process, for example at a height of 18inches. This would give service personnel an additional opportunity toensure that the area under the lift 10 is clear before the lift 10 iscompletely lowered to floor level.

The automotive lift 10 thus described is suitable for domesticautomotive vehicles. For commercial vehicles a lift 90 having a highercapacity may be required, in which case a third leg can be added to eachlift section as shown in FIG. 9, which illustrates the hydraulic systemfor such a lift. In this embodiment the hydraulic cylinders 70 arepositioned between the middle leg 30 and one of the front or rear legs30 of each lift section 92, and the piston shaft 72 is either coupled tothe middle sliding assembly 50 at an intermediate point or, preferably,formed from two sections which screw together at the sliding body 52associated with the middle leg 30. Otherwise the lift 90 operates in thesame fashion as the lift 10 described above.

A preferred embodiment of the invention having been thus described byway of example only, it will be apparent to those skilled in the artthat certain modifications and adaptations may be made without departingfrom the scope of the invention, as set out in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An automotive liftcomprising a pair of lifting sections, each lifting section comprisingadeck rail for supporting a vehicle, supported by at least two legs, eachleg havingan associated sliding assembly to which an upper portion ofthe leg is pivotally affixed, slidably mounted to the deck rail andhaving a path of travel along a portion of the length of the deck rail,and an associated link arm, having an upper end pivotally secured to thedeck rail at a fixed position spaced from the path of travel of thesliding assembly and a lower end pivotally secured to an intermediateportion of the leg, and an actuator for applying a force to each slidingassembly, whereby the actuator forces each sliding assembly to movetoward its associated link arm to alter an angulation between the legrelative to the deck rail.
 2. The automotive lift of claim 1 in whichthe lower end of the link arm is pivotally secured to the leg atapproximately the midpoint of the leg, so that the deck rail risessubstantially vertically.
 3. The automotive lift of claim 2 in which alength of the link arm approximately equals a length of the leg from theupper portion of the leg to a point at which the lower portion of thelink arm is secured to the leg.
 4. The automotive lift of claim 1 inwhich each deck rail has two legs.
 5. The automotive lift of claim 1 inwhich each deck rail has three legs.
 6. The automotive lift of claim 1in which the sliding assembly comprises a sliding body extending betweena pair of wings slidably received in channels formed in the deck rail.7. The automotive lift of claim 6 in which the sliding body is affixedto the wings by pins disposed through the upper portion of a leg.
 8. Theautomotive lift of claim 1 in which the actuator comprises a hydrauliccylinder.
 9. The automotive lift of claim 8 in which the cylindercontains a piston having a front portion which extends forwardly of thecylinder and is affixed to a front sliding body and a rear portion whichextends rearwardly of the cylinder and is affixed to a rear slidingbody.
 10. The automotive lift of claim 8 in which the cylinder actuatingone lifting section is connected in series with a cylinder actuating theother lifting section.
 11. The automotive lift of claim 1 in which eachsliding assembly is provided with a pair of brake arms retractable froman extended position in which the brake arms extend into slots providedin the deck rail to a retracted position in which the brake arms areretracted from the slots, the brake arms being biased toward the slotsand being retractable by a force applied to the brake arms.
 12. Anautomotive lift comprising a pair of lifting sections, each liftingsection comprisinga deck rail for supporting a vehicle, supported by atleast two legs, each leg havingan associated sliding assembly to whichan upper portion of the leg is pivotally affixed, slidably mounted tothe deck rail and having a path of travel along a portion of the lengthof the deck rail, and an associated link arm, having an upper endpivotally secured to the deck rail at a fixed position spaced from thepath of travel of the sliding assembly and a lower end pivotally securedto an intermediate portion of the leg, and a hydraulic cylinder securedat a fixed position on the deck rail to apply a force longitudinallyalong the deck rail, having a piston with a piston shaft extending fromforward and rear ends of the cylinder, a forward end of the piston shaftbeing coupled to a forward sliding assembly and a rear end of the pistonshaft being coupled to a rear sliding assembly, to move the forward andrear sliding assemblies in synchronous relation, the actuator forceseach sliding assembly to move toward its associated link arm to alter anangulation between the leg relative to the deck rail and thus raise thedeck rail.
 13. The automotive lift of claim 12 in which the lower end ofthe link arm is pivotally secured to the leg at approximately themidpoint of the leg, so that the deck rail rises substantiallyvertically.
 14. The automotive lift of claim 13 in which a length of thelink arm approximately equals a length of the leg from the upper portionof the leg to a point at which the lower portion of the link arm issecured to the leg.
 15. The automotive lift of claim 12 in which eachdeck rail has two legs.
 16. The automotive lift of claim 12 in whicheach deck rail has three legs.
 17. The automotive lift of claim 12 inwhich the sliding assembly comprises a sliding body extending between apair of wings slidably received in channels formed in the deck rail. 18.The automotive lift of claim 17 in which the sliding body is affixed tothe wings by pins disposed through the upper portion of a leg.
 19. Theautomotive lift of claim 12 in which the cylinder contains a pistonhaving a front portion which extends forwardly of the cylinder and isaffixed to a front sliding body and a rear portion which extendsrearwardly of the cylinder and is affixed to a rear sliding body. 20.The automotive lift of claim 12 in which a cylinder actuating onelifting section is connected in series with a cylinder actuating theother lifting section.
 21. The automotive lift of claim 12 in which eachsliding assembly is provided with a pair of brake arms retractable froman extended position in which the brake arms extend into slots providedin the deck rail to a retracted position in which the brake arms areretracted from the slots, the brake arms being biased toward the slotsand being retractable by a force applied to the brake arms.
 22. Anautomotive lift comprising a pair of lifting sections, each liftingsection comprisinga deck rail for supporting a vehicle, supported by atleast two legs, each leg havingan associated sliding assembly to whichan upper portion of the leg is pivotally affixed, slidably mounted tothe deck rail and having a path of travel along a portion of the lengthof the deck rail, the path of travel having at least one row of slotsextending along a portion of the length of the deck rail, and anassociated link arm, having an upper end pivotally secured to the deckrail at a fixed position spaced from the path of travel of the slidingassembly and a lower end pivotally secured to an intermediate portion ofthe leg, and an actuator for applying a force to each sliding assembly,whereby the actuator forces each sliding assembly to move toward itsassociated link arm to alter an angulation between the leg relative tothe deck rail, wherein each sliding assembly is provided with a pair ofbrake arms retractable from an extended position in which the brake armsextend into the slots to a retracted position in which the brake armsare retracted from the slots, the brake arms being biased toward theslots and being retractable by a force applied to the brake arms. 23.The automotive lift of claim 22 in which the lower end of the link armis pivotally secured to the leg at approximately the midpoint of theleg, so that the deck rail rises substantially vertically.
 24. Theautomotive lift of claim 23 in which a length of the link armapproximately equals a length of the leg from the upper portion of theleg to a point at which the lower portion of the link arm is secured tothe leg.
 25. The automotive lift of claim 22 in which each deck rail hastwo legs.
 26. The automotive lift of claim 22 in which each deck railhas three legs.
 27. The automotive lift of claim 22 in which the slidingassembly comprises a sliding body extending between a pair of wingsslidably received in channels formed in the deck rail.
 28. Theautomotive lift of claim 27 in which the sliding body is affixed to thewings by pins disposed through the upper portion of a leg.
 29. Theautomotive lift of claim 22 in which the actuator comprises a hydrauliccylinder.
 30. The automotive lift of claim 29 in which the cylindercontains a piston having a front portion which extends forwardly of thecylinder and is affixed to a front sliding body and a rear portion whichextends rearwardly of the cylinder and is affixed to a rear slidingbody.
 31. The automotive lift of claim 29 in which the cylinderactuating one lifting section is connected in series with a cylinderactuating the other lift section.
 32. The automotive lift of claim 22 inwhich each brake arm comprises a latching portion for engaging the slotsand an actuating portion rotatably fixed to the latching portion forretraction by the force applied to the brake arms.
 33. The automotivelift of claim 22 in which both brake arms are retracted by a shacklehaving slots for engaging fastening members affixed to actuatingportions of the brake arms.
 34. The automotive lift of claim 22 in whichthe force is applied to the brake arms by a pneumatic cylinder.